扫描电镜技术在高分子表征研究中的应用

扫描电子显微镜(scanning electron microscope,SEM)是表征高分子材料微观结构及其组成信息重要的手段之一,具有操作简便、信号电子种类多样且对样品损伤较小等特点.本文系统阐述了SEM的工作原理,通过与透射电子显微镜(transmission electron microscope,TEM)进行比较,突出了其优势与特色.详细讨论了该技术的测试方法,包括样品制备、仪器参数设定、操作技巧与图像处理,并揭示了获得高质量SEM图像的关键技术.介绍了SEM不同的信号电子成像、SEM与其他仪器联用及SEM原位分析技术在高分子材料表征中的应用与进展.最后,对SEM的发展趋势进行了展望.

Relationship between Localization of PBSU in Interlamellar/Interfibrillar Regimes and Double Peaks in DSC/SAXS in its Blend with PVDF

In this work,phase segregation and localization of PBSU have been investigated with the combination of SAXS and DSC in its blend with PVDF.After stepwise crystallization of PVDF and PBSU,there are double melting peaks of PBSU in DSC and double scattering peaks in SAXS.It has been demonstrated that double peaks can be attributed to the localization of PBSU in interlamellar/interfibrillar region in pre-formed PVDF crystal framework.In the case of low content of PBSU in blend,PBSU is trapped into the interlamellar region of PVDF crystals,resulting in the alternating lamellae crystal of them and the first peak(with low-q)in SAXS.The enhanced confinement effect produces thinner PBSU lamellae,corresponding to the lower melting temperature in DSC.Upon increasing its content in blend,some PBSU segregates in interfibrillar regions in addition to the enrichment in interlamellar regions of PVDF crystal framework.The larger space and higher concentration of PBSU in interfibrillarregions contribute to periodic lamellae structure of PBSU with higher thickness,which is the reason for the second peak(with high-q)in SAXS and DSC.Our results not only clarify the relationship between localization of PBSU in interlamellar/interfibrillar regions and double peaks in DSC/SAXS,but also provide a novel strategy to detect the interlamellar and interfibrillar segregation of low-T_(m) component in miscible crystalline/crystalline blend.